Southee has bowled brilliantly throughout the series, and has figures of 4-51 from Sri Lanka's innings on top of the four he picked up in the first innings of the first test (he didn't bowl in the second innings due to injury) and career-best figures of 7-64 in the second test against India in August. He's snared 16 wickets in his last three tests at an average of 14.31 - his career average is 36.21.
"I am going through a period now where it's coming out nicely and I'm managing to pick up some wickets but I think Trent Boult has a massive part to play in that as well," said Southee. "He's helped me out by building pressure at the other end and I'm sure his turn is just around the corner."
Boult has bowled without much luck in recent times and even yesterday saw a regulation catch from Tharanga Paranavitana spilled by Ross Taylor at first slip. He's bowling with pace and penetration but has picked up only eight wickets in his last four tests.
The wicket has offered something for the new ball bowler but is even-paced and comfortable for a batsman who can get himself in.
"The Sri Lanka run rate has been slower [than ours] so it just shows you that if you bowl in good areas it's not that easy to score," Southee said.
"It's definitely a new ball wicket. If you can grab a couple with the new ball, it definitely makes it easier and you can make in-roads into their batting lineup. Once the ball get's older, it tends to flatten out a wee bit."
Spinners Jeetan Patel and Todd Astle have picked up only one wicket between them in Sri Lanka's innings but could come into play more if New Zealand can set the home side a testing target on the fourth innings. The pitch is taking turn, although it's slow turn, but Patel and Astle could expect the wicket to deteriorate.